1. Compile and integrate city-wide data to contextualize and follow the HIV epidemic among IDUs and other high-risk drug users in NYC; and 2. Establish a sentinel monitoring station in the Lower East Side of NYC to a. Provide current information regarding changes in community trends/influences which can assist projects in interpreting findings; b. Establish a local community monitoring model, similar to NIDA's Community Epidemiology Working Group, for ethnographic and data-based monitoring of local community changes influencing drug use and HIV; and c. Collect serosurvey data on high-risk drug users to complement data from the funded projects.